EVIDENCE FOR A PARENT-OF-ORIGIN EFFECT ON SPERM ANEUPLOIDY IN MICE CARRYING ROBERTSONIAN TRANSLOCATIONS AS ANALYZED BY FLUORESCENCE IN-SITUHYBRIDIZATION

Multi-color fluorescence in situ hybridization (FISH) was employed to investigate variations in the frequency of aneuploid spermatids produc ed by males derived from three separate lines of Robertsonian transloc ations in mice: Rb(2.8)2Lub, Rb(8.12)22Lub, and Rb(8.14)16Rma, each wi th one arm involving chromosome 8. The DNA probes used were specific f or repetitive sequences on chromosomes 8 and X. Heterozygous males for these Robertsonian translocations produced similar to 1% of spermatid s with hyperhaploid for chromosome 8, which was > 80 times higher than the frequency of sperm hyperhaploid for chromosome X within the same animals; consistent elevations in chromosome-8 sperm disomy were obser ved among lines. In addition, similar to 25% higher fractions of sperm aneuploidy were observed when the Robertsonian translocation was inhe rited from the father rather than from the mother(p = 0.009). These fi ndings illustrate the sensitivity of the FISH procedure for detecting small differences in the hyperhaploidy in male germ cells and suggest that imprinted factors may influence sperm aneuploidy.